Month: January 2016

Retrieving Geocodes from ZipCodes using Python and Selenium

Alternative to using GoogleMapAPI to retrieve the geo codes (Latitude and Longitude) from zip codes. This website allows batch processing of the zip code which make it very convenient for automated batch processing.

Below illustrate the general steps in retrieving the data from the website which involve just enter the zipcode, press the “geocode” button and get the output from secondary text box.

Batch Geocode processing website

The above tasks can be automated using Selenium and python which can emulate the users action by using just a few lines of codes. A preview of the code are as shown below. You will notice that the it calls each element [textbox, button etc] by id. This is also an advantage of this website which provide the id tag for each required element. The data retrieved are converted to Pandas object for easy processing.

Currently, the waiting time is set manually by the users.  The script can be further modified to retrieve the number of data being processed before retrieving the final output. Another issue is that this website also make use of GoogleMapAPI engine which restrict the number of query (~2500 per day).  If require massive query of data, one way is to schedule the script to run at fix interval each day or perhaps query from multiple websites that have this conversion features.

For my project, I may need to pull more than 100,000 data set. Pulling only 2500 query is relatively limited even though I can run it on multiple computers. Would welcome suggestions.


import re, os, sys, datetime, time
import pandas as pd
from selenium import webdriver
from selenium.webdriver import Firefox

from time import gmtime, strftime

def retrieve_geocode_fr_site(postcode_list):
    """ Retrieve batch of geocode based on postcode list.
        Based on site: http://www.findlatitudeandlongitude.com/batch-geocode/#.VqxHUvl96Ul
        Args:
            postcode_list (list): list of postcode.
        Returns:
            (Dataframe): dataframe containing postcode, lat, long

        NOte: need to calcute the time --. 100 entry take 94s

    """
    ## need to convert input to str
    postcode_str = '\n'.join([str(n) for n in postcode_list])

    #target website
    target_url = 'http://www.findlatitudeandlongitude.com/batch-geocode/#.VqxHUvl96Ul' 

    driver = webdriver.Firefox()
    driver.get(target_url)

    #input the query to the text box
    inputElement = driver.find_element_by_id("batch_in") 
    inputElement.send_keys(postcode_str)

    #press button
    driver.find_element_by_id("geocode_btn").click()

    #allocate enough time for data to complete
    # 100 input ard 2-3 min, adjust according
    time.sleep(60*10)

    #retrieve ooutput
    output_data = driver.find_element_by_id("batch_out").get_attribute("value")
    output_data_list = [n.split(',') for n in output_data.splitlines()]

    #processing the output
    #last part create it to a pandas dataframe object for easy processng.
    headers = output_data_list.pop(0)
    geocode_df = pd.DataFrame(output_data_list, columns = headers)
    geocode_df['Postcode'] = geocode_df['"original address"'].str.strip('"')
    geocode_df = geocode_df.drop('"original address"',1)

    ## printing a subset
    print geocode_df.head()

    driver.close()

    return geocode_df

 

 

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